This blog is for Mormons who have questions about vaccines, though anyone is welcome! Much of the research is relevant to anyone.

Friday, August 19, 2011

The Big Post on Herd Immunity (Mooooooo!)

Herd Immunity

This will be a disappointing post to many people, no doubt. Have you been waiting for me to say, “Don’t get vaccinated because herd immunity will protect you”? Well that won’t be happening because the concept of herd immunity does not have any grounding in research. Oh sure, we can point to the fact that there are high immunization rates now and low rates of diseases like measles and pertussis. And because vaccination has created low rates of these diseases, everyone is protected, even those who haven’t been vaccinated. But is that an entirely logical argument? First of all, let’s tackle the argument that high rates of vaccination eliminate diseases. A 1953 report from the Office of Vital Statistics showed a decline in deaths from infectious diseases, including measles, diphtheria, pertussis and scarlet fever during the first half of the 20th century. The report does mention vaccination programs as contributing to the decline (though vaccines did not exist or were only very recently introduced for most of the diseases mentioned in the report), but also mentions improved sanitation in water and milk supplies, cleaner sewage disposal in rural areas, and improvements in diet, hygiene, and medical care as being major contributors to the dramatic decline in infectious diseases. The whole cell DTP vaccine for diphtheria, tetanus, and pertussis was first licensed in 1949, but the charts in the report show that diphtheria deaths had declined dramatically between 1900 and 1945 and by 1942 had reached less than 1 per 100,000. Pertussis deaths declined from about 17 per 100,000 in 1918 to less than 1 per 100,000 in 1945. (1)

The CDC’s official statement on measles reads: “In the United States, measles caused 450 reported deaths and 4,000 cases of encephalitis annually before measles vaccine became available in the mid-1960s.” (2) In 1955 the death rate from measles was .03 per 100,000. (3). These numbers are congruent with the charts in the above mentioned report. With a population of about 165,931,202 in 1955, this would mean that there were only about 50 deaths from measles in the United States that year. Obviously, 450 deaths was true in the early years of the twentieth century, but by 1955 (eight years before the vaccine was introduced), the number of measles deaths was far fewer than what the CDC is quoting. Measles enchephalitis is said to occur in 1 of every 1,000 cases of measles, however, many physicians who actually practiced when measles was common questioned this statistic and put the rate of encephalitis at 1 in 10,000 to 1 in 100,000 for children who are adequately fed and living in sanitary conditions (3).

The Haemophilus Influenza B vaccine is often used as an example of how vaccines directly impact cases of disease, because the rates of Hib declined the year after its licensure. But the 1994 Vandheim study showed that the incidence of Hib disease in infants in the Los Angeles area decreased in the year prior to the vaccine’s licensure for infants. Texas also noted dramatic declines in Hib, but these also began before the vaccine’s licensure. Studies in Minnesota showed the vaccine to be ineffective. (4).

Also note that vaccinations have not eliminated disease in less-developed countries. Despite Bill Gates donating $700 million to a polio vaccination campaign in Nigeria, which included door-to-door vaccinators, polio still persists in Nigeria and in fact, half of the 1,600 cases of polio reported in 2009 occurred in vaccinated individuals. (5) Evidence points to fully vaccinated children transmitting polio during a 1988-1989 outbreak of the disease in Oman. (6) A case study from India documents a measles outbreak in a slum. Almost one-third of the children who contracted measles were vaccinated for the disease. This study also found that children who had vitamin A supplementation were less likely to contract measles. (7) So the argument that “vaccines eliminated diseases because before vaccines were used disease ran rampant and after vaccines were used these diseases became rare” is not correct because statistics show that the diseases we vaccinate for were on the decline before mass vaccination. In rhetoric, this kind of logical fallacy is called Post Hoc, Ergo Propter Hoc, (which is Latin for “after this, therefore because of that”) occurs where one mistakenly assumes that because the first event preceded the second event, that the first event caused the second event, as is the case here.

Furthermore, think about the argument that is commonly made in favor of herd immunity: "Vaccines protect individuals from disease by stimulating the immune system to give an immune response so that the disease doesn't take hold. But vaccines only work if a majority of people receive them. If some people don't get vaccinated, then vaccines will stop working." In rhetoric, this kind of claim would be classified as a contradictory premises or logical paradox; if one condition exists, then the other cannot. If vaccines really protect individuals, then their welfare shouldn't be dependent on others getting the shots. Or if vaccines only work on a group basis, then you couldn't argue that they will protect individually as well. Also, if herd immunity were true, then we should have seen rampant disease in decades past because most adults no longer carried immunity from their childhood shots.

Then there is the idea that herd immunity eradicates diseases. Where do these diseases go? Do they simply die off because everyone has immunity to them? Do they evolve and mutate to infect us as another strain? No one has yet addressed this topic.

Herd immunity is not a reality. Preventing disease is a matter for the individual.

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Disclaimer

The information herein is my own research and the opinions expressed herein reflect my views and are not representative of the LDS Church. This information is not intended to be used to diagnose, prevent, cure or treat any health condition(s), if you have a health condition please see a qualified practitioner for advice.